JPS5941370A - White ink composition for ink jet recording - Google Patents

Abstract

PURPOSE:To provide titled composition of adequate viscosity and resistivity and highly stable dispersibility, capable of clear printing on such dark and/or black color-based items as wood, steel plate and pipe, comprising a colorant consisting of white pigment of specific particle size, solvent, and integrating resin. CONSTITUTION:The objective composition comprising, preferably (A) 5-40wt% of a white pigment with a particle size <=3mum (pref. titanium dioxide), (B) 55- 90wt% of an organic solvent such as ethanol, methylethyl ketone (pref. containing 2-10wt% of an acetic acid ester), (C) 0.3-1.0pt.wt. per 1pt.wt. of the white pigment, of an integrating resin such as a rosin-modified maleic acid resin or ketone resin, and (E) 0.25-5wt% of a resistivity regulator for bringing the resistivity of the final ink to 2,000OMEGA.cm or lower (e.g., lithium nitrate, sodium thiocyanate). USE:For steel plate provided with corrosion-proof treatment, oxidized film-coated steel plate, tin-deposited iron plate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink used in an inkjet printing system, particularly for printing on colored or transparent materials such as wood, metal, plastic, glass, ceramics, leather, and surface-treated cardboard. The present invention relates to suitable ink compositions.

In the inkjet recording method, the ink must have the ability to stably form particles, receive electrical signals, and form a desired recording on an object. Therefore, the general property range desired for the ink composition under the usage conditions (51Z' to 40C) is as follows.

Viscosity = 1~15 cp Surface Tension Crab 20~60 dyn/z Resistivity: Below 2000 Ω-m Specific Gravity: 1~3 Furthermore, it is stable for long periods of time and does not cause clogging of nozzles or filters during use. It is required to be able to print with the necessary and sufficient precision and total density by adhering to the surface of the substrate.

Conventionally, there are two types of inkjet recording ink: systems that use water as the main dispersion solvent and systems that use organic solvents, and colorants (pigments) that are soluble in each solvent have been used. This is an ink that is intended for printing on a white or similar substrate, and if the substrate is strongly colored, the printing itself will be hidden by the color of the substrate, and the printing will be difficult. The problem was that it became illegible.

As an inkjet recording ink that can be printed on metal, glass, rubber, etc., and is made entirely of organic solvents, e.g.
1972-54147, 1972-50935, 1972-96106, 1972-138208. No. 55-50073 and the like are disclosed. these are,
Since the colorant used is limited to black or chromatic colors, it is not suitable for printing on blackish objects. Furthermore, up until now, inkjet recording inks have been used regardless of whether they are water fl-based or organic solvent-based.
No white ink suitable for printing on a black background has been proposed.

Printing on objects that are entirely black is well known in the technical field of paints and inks, and a white pigment with strong permeability is mainly used as a coloring agent. However, paints are generally too viscous; on the other hand, there are 7-Elpen inks, which have low viscosity and fluidity that allows them to pass through the inside of felt, but if they are left standing for a long time, the pigments Prone to sedimentation. Also, no special consideration has been given to their resistivity. Based on such products, it has been difficult to prepare inkjet recording inks having the above-mentioned properties necessary for receiving electrical signals and forming particles. In particular, the addition of salts to lower the resistivity and the lowering of the viscosity of the ink to make it easier to form particles can cause the dispersion of pigment particles to aggregate and become coarser, making them more likely to settle and clog nozzles, filters, etc. That was the problem.

The present invention was made as a result of various studies on pigment particle size, resistivity adjuster (conductivity imparting agent), and other ink components in order to balance properties such as fluidity, resistivity, and dispersion stability of pigment particles. Our goal is to provide a complete range of inkjet recording inks that can print clearly even on objects with dark or black backgrounds.
Contains an organic solvent, a binding resin, and a resistivity adjuster, and has a resistivity of 2000 Ω・m or less and 1 to 15
In an inkjet recording ink having a viscosity of CP, titanium oxide was used as a colorant. #Titanium oxide is used with a particle size of 3 μm or less, and the titanium oxide content of the ink is preferably adjusted to 5 to 40% by weight.

In the present invention, the particle size of titanium oxide is preferably adjusted to 3 μm or less, preferably 0.5 to 0.7 μm, from the viewpoint of dispersion stability. It has been found that titanium oxide exhibits strong adhesion even in particle sizes as small as this, and does not aggregate during the ink drying process after printing. The amount of i-edge titanium in the ink can be increased from 5% to 40% by weight,
Prints with sufficiently legible density can be obtained even at 5% printing.

However, in order to completely mask the color of the printed material, the M' content of titanium oxide must be about 15 weight percent or more.

In addition, if the 1i is 40% by weight or more, the viscosity of the ink)
15 rose rapidly, and although various combinations of binder resin and organic solvent were tried, it was found that the value exceeded 150P. This is because the interaction between the titanium oxide particles increases and the shielding effect of the titanium oxide particles by the solvent or resin is lost.

In the present invention, the action of the binding resin is to give the ink a stable viscosity (1 to 15 cP), wrap around the titanium oxide, and give a charge* to the titanium oxide particles.
It obstructs particle collection and causes Brownian motion to prevent sedimentation, exhibits strong adhesion to the printed material after printing, and maintains the image quality of the print with a constant spread at all times. be. Binding resins that are particularly good for titanium oxide include rosin-modified maleic acid resins, xylene resins, rosin-modified xylene resins, ester gums, ketone (shugetsuji), nitrocellulose, novolac-type and resol-type phenolic resins, rosin-modified Phenol resin, alkylphenol resin, terpene-modified phenol resin, rosin glycerin ester, rosin polyethylene non-glycol ester, hydrogenated rosin oyohysonoester, acrylic acid, methacrylic acid and resins made of their alkyl esters, and other acrylic resins. etc. The above resins are 0.1 to 0.1 to titanium oxide.
It is used in an amount of 5 times, and a 0.3 to 1.0 times amount is particularly effective for improving viscosity and preventing agglomeration of titanium oxide.

Regarding organic solvents, alcohols are mentioned first, such as methanol, ethanol, 2-propanol, 1-propanol, and butanol.

These alcohols regulate the drying rate of the ink after printing, control the bottom surface tension of the ink, adjust the viscosity, solubility of the resistance modifier, etc., and further determine the stability of titanium oxide.

Also preferred are ketones such as methyl ethyl ketone and methyl imbutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol diethyl ether. These have the effect of strengthening the adhesion of the resin on the surface of the printed material, and during printing, even if the ink droplets fly and collide with the printed material, they do not scatter as ink, and the printed dots are uniformly coated. This is particularly effective in maintaining the diameter. In addition, they help the interface between the resin and titanium oxide and the effect that the resin covers the titanium oxide, and are highly effective in improving the dispersion stability of pigment particles. Furthermore, acetic acid esters such as ethyl acetate and butyl acetate are particularly effective on the dispersion stability of titanium oxide. The organic solvent is used in an amount of 55 to 90% by weight based on the total ink so that the viscosity of the ink falls within a desired range. The proportion of acetic acid esters contained therein is suitably 2 to 1 oM%.

In the present invention, the resistance adjuster increases the resistivity of the ink by 20
This is essential in order to adjust to 000·On or less. Examples include sodium, potassium and ammonium chlorides and other alkali halides, alkali metal and alkaline earth metal thiocyanates and acetates.

Such salts aggregate dispersed pigment particles, as described above.
It has the potential to cause coarsening. Among them, lithium nitrate and sodium thiocyanate are particularly superior in that they do not inhibit the dispersibility of titanium oxide, and the dispersion stability of the pigment is about 10 to 20 times higher than that of lithium chloride, sodium chloride, potassium nitrate, etc. shows. The resistance adjuster can satisfy the above-mentioned resistivity requirements if it is contained in the ink in an amount of about 0.25% by weight or more, and even if it is present in a large amount, no advantage is exhibited.

A surfactant can further be added to the ink of the present invention. By controlling the bottom surface tension of the ink and setting it equal to, or even lower than, the bottom surface tension of the same phase of the printing object, extremely excellent printing quality can be obtained. Examples of the surfactant include metal soaps such as lead, zinc, barium, zirconium, and cobalt salts such as naphthenic acid, stearic acid, and octenoic acid that are soluble in the above solvents, fluorine-based surfactants, silicone surfactants, and polyoxylic acid. Alkylene derivatives, sorbitan alkyl esters, polyoxyfulvitan alkyl esters, etc. have great effects. The amount of surfactant used is 0.0 based on the entire ink.
1 to 5% by weight is desirable.

The ink of the present invention forms clear prints on objects made of various materials such as black or transparent under the same conditions as conventional ones (approximately 5 to 40 C) using an inkjet printing device with normal functions except for increasing the ejection pressure to about 5 atm. can. Printed materials include steel plates, rust-proofed copper plates, copper plates coated with oxidation through chemical conversion treatment, steel plates with a triiron tetroxide coating formed by high-temperature oxidation, tin-plated iron plates, and surfaces made of thermosetting resin or thermoplastic resin. Iron plates coated with iron and iron pipes treated with the above treatment, iron acid, castings, plates with aluminum surfaces, pipes, molds, and various other metal products, coloring agents, fillers, and reinforcing agents that give p-black and strong Colored thermoplastic and thermosetting resins and rubber products, oxidized nail mold resin, automobile tires, electronic parts molded with black resin, as well as transparent plastic containers, glass plates and containers,
Vases, syringes, color cathode ray tubes, fluorescent lights, beer bottles,
Examples include pottery and porcelain. Of course, the scope of application of the ink of the present invention is not limited to the above.

Next, examples of the present invention will be shown.

Example 1 Titanium oxide (methyl type, manufactured by Ishihara Sangyo, average particle size, 0.4μ
15 parts of xylene resin (manufactured by Mitsubishi Gas Chemical) dissolved in 7 parts of cyclohegginone was dispersed in 15 parts of powder (M powder) for 1 hour using a paint shaker (manufactured by Toyo Seiki), and then mixed with 1.5 parts of sodium thiocyanate. Add 100 parts of methyl ethyl ketone,
Mix the bones in a ball mill for 30 minutes. Filter with suction through a 3 μm filter to remove coarse particles. Furthermore, 50 parts by weight of methyl ethyl ketone containing 065 parts by weight of zinc octate are added and mixed by shaking. In this way, an ink with properties suitable for use as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 5.
Oc P (20C), surface tension 32 dyne/cr
n, resistivity 320 Ω'' and tm specific gravity 1.05. In an inkjet injection device with a nozzle orifice diameter of 75 μm, a normal device was used except that a pressure of 4.5 Kp/crn was applied to 0. Prints by jetting ink. By applying vibrations of 118 kHz, characters of 28 vertical dots x 28 horizontal dots can be printed. Printing was performed using glass, black plastic, or a steel plate with a high-temperature oxide film as the printing target.

In either case, the printing is good, and drying is completed after 80 to 120 seconds of exposure, and it does not come off even when rubbed with fingers, and does not stain fingers. In the case of glass (general soda glass for social glass, one side opaquely treated), the diameter of the ink dots printed on the smooth surface after drying was 95 μm. The diameter of the dots on the matte surface (frosted glass surface) was 160 μm. In all cases, the white color had sufficient hiding power and the printed characters were clearly legible. As other samples, when printing was made on a polycarbonate molded plate containing 7% carbon powder, which is a black plastic, and a molded plate made of acrylonitrile-butadiene-styrene (ABS) resin containing 12% carbon powder, the diameter of each print was 220 mm. , 240 μm. In this case as well, there was no bleeding and a good white print was obtained.

Example 2 Titanium oxide (rutile type 1 manufactured by Ishihara Sangyo, average particle size 0.4 μm)
(powder) ・Former group...15M1K part rosin-modified xylene resin (Mitsubishi Gas Chemical)...
・・・・・・40 Cyclohexanone ・・・・・・・・・・・・6
0 ethanol ・・・・・・・・・・・・
20 The above material was passed through a sand mill twice to disperse it, 50 parts of ethanol and 20 parts of sodium thiocyanate were added, and the mixture was stirred for 30 minutes using a Beau Novel.

Filter by suction through a 3 μm filter to remove coarse particles. Further, 740 parts by weight of methyl ethyl ketone containing 0.5 parts by weight of zinc octate are added, and the mixture is stirred by stirring.

As a result, an ink having characteristics that can be used as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 8.3 c P (20r) and a surface tension of 4
It exhibited a 3 dyne/crns resistivity of 500Ωa z and a specific gravity of 1.1. Also, as in Example 1, good results were obtained in printing with an inkjet recording device.

Example 3 Titanium oxide (rutile type 1 manufactured by Ishihara Sangyo, average particle size 0.4 μm)
(powder) 13 parts by weight Rosin-modified maleic acid (Hitachi Chemical) 4.0 Nitrocellrone (Daicel Ll/4) 2.0 Cyclohexanone・・・・・・・・・・・・
20 Ethanol ・・・・・・・・・
・・・・・・42 Ethyl acetate ・・
・・・・・・・・・・・・・・・ 5 Methanol
・・・・・・・・・・・・・・・・・・ 5. Pass the above product twice in a sand mill to disperse it, add 72 parts of ammonium thiocyanate and 100 parts of ethanol, and stir thoroughly. Filter by suction through a 3 μm filter to remove coarse particles. Furthermore, 40 parts by weight of ethanol containing 0.5 parts of zinc octate was added and mixed by shaking.

As a result, an ink having characteristics that can be used as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 2.1 CP (20C) and a surface tension of 2
3 dyne 7cm, resistivity 1050Ω”on.

It showed a specific gravity of 1.04. Further, as in Example 1, good results were obtained in printing using an inkjet recording device.

Example 4 Titanium oxide (rutile type 9 manufactured by Ishihara Sangyo, average particle size 0.4 μm)
(powder) ...... 11 parts by weight Ester gum (manufactured by Fuyorin Sangyo) ...Dan 4.3 cyclohexanone ...Dan 43 ethanol ...... 40 Ammonium thiocyanate 1.5 Disperse the above in a ball mill for 15 hours, add 7100 parts of methyl ethyl keto, fill and stir, then suction filtrate through a 3 μm filter to remove coarse particles.

As a result, an ink having characteristics that can be used as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 1.8 cP (20t?), a surface tension of 35 dyne 7 cm, and a resistivity of sooΩ”ffi.
, has a specific gravity of 1.11. Further, as in Example 1, good results were obtained in printing using an inkjet recording device.

Example 5 Titanium oxide (rutile type 1 manufactured by Ishihara Sangyo, average particle size 0.4 μm)
powder) - Old...20 parts by weight Ketone resin (manufactured by Hitachi Chemical) - Old...2゜Methyl ethyl ketone...50 ethyl ketone
・・・・・・・・・・・・10 Sodium thiocyanate ・・・・・・・・・・・・ 2 Disperse the above in a paint shaker (manufactured by Toyo Seiki) for 2 hours. Thereafter, 7100 parts of methyl ethyl keto was added, thoroughly stirred, and suction filtered through a 3 μm filter to remove coarse particles.

As a result, an ink having characteristics that can be used as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 9.8 c P (20 tT), an optical surface tension of 51 dyne/cm, a resistivity of 430 Ω·m1, and a specific gravity i.
It showed 1.21. Further, as in Example 1, good results were obtained in printing using an inkjet recording device.

Example 6 Titanium oxide (rutile type 1 manufactured by Ishihara Sangyo, average particle size 0.4 μm)
(powder) 40 parts by weight Rosin-modified maleic acid (manufactured by Hitachi Chemical) 15 Methanol 40 parts by weight
・10 Ethanol ・・・・・・・・・
・・・・・・12 Isoproper Tools ・・・・・・
・・・・・・20Ethyl acetate ・・・
5. Disperse the above ingredients in a paint shaker (manufactured by Toyo IrR Machine) for 2 hours. After that, 100NS of ethanol and 2 parts of lithium nitrate were added and stirred thoroughly.
Suction filtration is performed using a 3 μm filter to remove phase particles.

With this result, an ink usable as an ink for inkjet recording was obtained. That is, the above (D'(7" is viscosity 13.5 c P (2QC), table lff1 tension 27, 5 dyne/tyn, yield rate 910 Ω")
cm, specific gravity 1,5 (r=indicated. Also, as in Example 1, good results were obtained when printing with an inkjet recording device.Continued from page 1 ■Applicant Dainichiseika Kogyo Co., Ltd. Chuo-ku, Tokyo Nihonbashi Bakurocho 1-7-6 procedural amendment (voluntary) I'I'j'l licho'l'! Lord Kazuo Wakasugi,
１′１のノ、小昭"'""l't'＋'j'l"('rl 1st
35166 It name of the invention (4. White ink composition for inkjet recording and inkjet recording method?+lid name 'I+f'l=]ll', II# moving1f'lout1
．． 9r! Meeting with people (former 51++l1)11
1-2 Special ν Work Name (2821 Dainichiseika Kagyo Co., Ltd. Pll Name of the Invention of the Invention of the Internally Amended Specification for Person Supplement) Inkjet GI: = = 舃γink Claim 1 Coloring agent, 1. A white ink composition for inkjet recording, comprising a solvent and a binding resin, wherein the bath material is a white pigment having a particle size of 3 μm or less.

2. The white ink composition for inkjet recording according to claim 1, wherein the white pigment is titanium oxide, and the titanium oxide content in the ink composition is 5 to 40 iJ.

How to record.

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an ink used in an inkjet printing system, and particularly relates to an ink used in an inkjet printing system, and particularly to wood, metal such as plate-like or tubular iron-copper, plastic, glass, ceramics, and leather parts 1 that have been surface-treated. The bonded article with cardboard 4 relates to a white ink composition suitable for inkjet printing of transparent articles and the use of this white ink composition for inkjet printing.

[Invented from the Ming Dynasty]

Inkjet b [When the ink used in the printing method is ejected from a nozzle, the ink particles are turned into particles by vibrations applied to the nozzle, and the resulting ink particles are charged according to an electric character signal, and passed through the applied deflection electrode. Underwater VC - A device that receives deflection in response to a fluorocarbon ayu and prints predetermined characters on a Japanese cypress print.

For this reason, in the inkjet recording method, the ink must stably form particles and receive electrical character signals to ensure the ability to form a desired record on an object. Therefore, the following basic requirements are desired for the ink composition when used at a temperature of 50 to 4oC.

Viscosity: 1 to 15 CP Surface tension = 20 to 60 dyn/cm Resistivity: 2000 Ω・m or less Specific gravity: 1 to 3 In addition, the ink is homogeneous and stable for a long period of time, and does not cause clogging of nozzles or filters during use. +J to the object forcefully
It is required to quickly dry, print, and print with exact precision and density.

Conventionally, inkjet recording inks include systems that use water as the main dispersion solvent and systems that use organic solvents, and pigments have been used as colorants soluble in each solvent. All of these inks are intended for printing on white or similar objects, and if the substrate is strongly colored, the printing itself will be hidden by the color of the substrate. Otherwise, the print becomes illegible.

Inkjet recording inks containing organic solvents as a main component and capable of printing on metal, glass, rubber, etc. are disclosed, for example, in JP-A-46-54147, JP-A-49-50935, and JP-A-52-96106.

lj'l Publication No. 52-138208, No. 55-500
Publication No. 73 is disclosed. These are because the colorant used is black or chromatic,
It was not suitable for marking M111 on black-colored articles.

Printing on objects that are mainly black is well known in the technical field of sugar pigments and inks, and white pigments with strong permeability, such as titanium oxide, are mainly used as coloring agents. However, in general, paints have a high viscosity, while inks have low viscosity and pass through the inside of felt, such as ink for felt-tip pens, which tends to cause pigment sedimentation if left for a long time. Also, they have been gendered in terms of resistance. Based on such paint ink,
When attempting to prepare an inkjet recording ink that has the above-mentioned characteristics necessary for receiving and converting electrical signals, it is found that, for example, it is most difficult to use an inkjet recording ink that uses titanium oxide as a white pigment. The problem is long-term operation, and there are two problems:

(1) Uniform pigment dispersion and maintenance of suspension in ink (2)
In order to solve the problem of filter clogging and pigment thicket/crime (1), it is necessary to constantly stir the ink mechanically, and to increase the ink flow by reducing the diameter of the tube in the ink supply system. For problem (2), it is necessary to remove the agglomerated pigment using a special filter. In any case, additional measures were required, and even with such measures, there were problems with the long I stability of the ink.

Additionally, attempts have been made to add salts to lower the resistivity and to lower the viscosity of the ink to make it easier to form particles.
The problem is that the dispersed pigment particles tend to aggregate and become coarse, causing sedimentation and clogging of nozzles, filters, etc.

In other words, no white inkjet recording ink suitable for printing on black backgrounds, whether water-based or solvent-based, has been put to practical use.

[Purpose of the invention]

An object of the present invention is to provide a single white ink stream for inkjet recording that can clearly print on dark-colored or black plate articles having excellent viscosity, electrical resistivity, and stable dispersion of pigment particles.

Another object of the present invention is to use this ink thread 1 composition for dark to rI colored articles (ink jet recording).

[Summary of the invention]

The purpose of Kosai 1 et al. is Δ4, and according to the invention, at least a coloring agent.

This can be achieved by using a white ink supply system for inkjet recording consisting of a solvent and a binding resin, in which the colorant is a white pigment with a particle size of 3 μm or less.

The white pigment used in the composition of the present invention is determined by particle size distribution measurement (Co
ulter counter model TAII
n1ade by COu 'le r fi l
e C1r On I CS + In C, U S
A) It is essential to use particles with a particle size of 3 μm or less (excluding 3 μm), preferably 0.5 to 0.07 μm, from the viewpoint of dispersion stability, redispersibility, printing stability, and nozzle clogging. be.

White pigment used in the present invention f'i titanium oxide, zinc white.

These are lithopone, white lead, zinc sulfide, basic lead sulfate, zirconium oxide, white antimony, and tin oxide, and they are used alone or in mixtures. In particular, titanium oxide was found to exhibit strong adhesion and not to agglomerate during the printing ink drying process.

Each of the white pigments used in the composition of the present invention
Table 1 shows the olor 1ndex JP6 and the plows that contain the planer.

Even when the white pigment in the ink composition is used at the lower limit value in the above table, prints with sufficiently legible density can be obtained.

However, to completely blacken the color of the printed material.

For example, the titanium oxide containing leaf needs to be at least about 15% titanium oxide. In addition, when 1↑ is made higher than the upper limit in the table above, the viscosity of the ink rises rapidly.
It was found that it exceeds.

This is because the interaction between the white pigment particles becomes thicker, and the effect of shielding the white pigment particles by the solvent or resin is lost.

In the present invention, the action of the binding resin is to give the ink a stable viscosity (1 to 15 CP), to wrap around the white pigment and to charge the white pigment particles, thereby preventing particle agglomeration and preventing Brownian motion. The objective is to prevent sedimentation by causing the ink to form, to exhibit strong adhesion to the printed material after printing, and to maintain a constant image quality of the print with a constant spread at all times. Binding resins that are particularly good for white pigments include rosin-modified maleic acid resin, xylene resin, rosin-modified xylene 14 resin, ester gum,
Ketone IVY BFI, nitrocellulose, novolac type and resol type phenolic resins, logi/modified phenolic resins, alkyl phenolic resins, terpene modified phenolic resins, glycerin esters of rosin, polyethylene glycol esters of rosin, hydrogenated rosin and its esters, acrylic acid, There are various acrylic resins including resins made of methacrylic acid and their alkyl esters. The above-mentioned binding resin is used in an amount of 0.1 to 5 parts by weight based on the itt part of the white pigment, and 0.3 to 1.0 parts by weight is particularly effective for improving viscosity and preventing agglomeration of the white pigment. shows.

The organic solvents used in the present invention include alcohols such as methanol, ethanol, 2-propanol, 1-propanol, and butanol. These alcohols control the drying rate of the ink after printing, the surface tension of the ink, the viscosity of the ink, the solubility of the resistance modifier, etc., and roughly determine the stability of the white pigment. Also, ketones such as methyl ethyl ketone and methyl imbutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, 4-71. stomach. These have the effect of strengthening the adhesion of the resin on the surface of the printing material, and when printing, they create a certain uniform radius on the printing dots so that the ink droplets fly and collide with the printing material and scatter as ink. This is particularly effective for maintaining In addition, they are effective in improving the dispersion stability of pigment particles by assisting the interface between the binder resin and the white pigment (Vl), and improving the dispersion stability of the pigment particles. Acetate ethers such as butyl are particularly effective for the dispersion stability of white pigments.

The organic solvent is used in an amount of 55 to 90 weight 14=1 for the entire ink, taking into account the 79+ desired viscosity of the ink. When used in combination with other organic solvents, the proportion of acetic esters contained in the solvent is 2 to 10% by weight, and the total aM is 55% by weight.
~Become 90 years old.

In the present invention, the resistivity adjusting agent increases the resistivity of the ink by 2.
Used to adjust to 000Ω・σ or less.

Examples include chlorides and other alkali halides of sodium, potassium and ammonium, thiocyanates and nitrates of alkali metals, alkaline earth metals and ammonium. Such salts have the possibility of making the dispersed pigment particles coarser and coarser, as described above. Among them, lithium nitrate and sodium thiocyanate are particularly superior in that they do not inhibit the dispersibility of white pigments, and compared to lithium chloride, sodium chloride, potassium nitrate, etc.
The dispersion stability of the pigment is about 10-20 times greater. Resistivity,
The modifier is present in the ink at least about 0.25% on a composition basis.
If the amount of ttII is at most 5% by weight, the above-mentioned resistivity requirement can be satisfied, and even if a large amount is present, no failure point will be shown.

A surfactant can further be added to the ink of the present invention. By controlling the surface tension of the ink and setting it equal to or lower than the surface tension of the solid phase of the broken font, extremely excellent printing quality can be obtained. Examples of the surfactant include metal soaps such as lead, zinc, barium, zirconium, and cobalt salts such as heptanoic acid, stearic acid, and octenoic acid, fluorine-based surfactants, silicone surfactants, and polysilicon surfactants that are soluble in the above-mentioned solvents. Oxyalkylene derivative, sorbitan alkyl ester.

It is a polyoxysorbitan alkyl ester. When using a surfactant, it is preferable to use a surfactant of 001 to 5 or more for the entire ink.

The white ink composition of the present invention can form clear prints on objects made of various materials such as black or transparent under the same conditions as conventional ones (approximately 5 to 40 C) using a normally functioning inkjet printing device with an injection pressure of approximately 5 atm. . Printed materials include steel plates, rust-prevention treated copper plates, steel plates coated with oxidation through chemical conversion treatment, copper plates with triiron tetroxide coating formed by high-temperature oxidation, tin-plated iron plates, and surfaces made of thermosetting resin or thermoplastic resin. Iron plate nuclided with iron plate and iron pipe treated with the above treatment, iron acid, iron material, plate with aluminum IC surface, pipe,
Molds and other metal products, thermoplastic and thermosetting resins colored black or strong chromatic colors with coloring agents, fillers, and reinforcing agents, rubber products, oxidative polymerization type resins,
Automobile tires, electronic parts sealed with black resin,
Further examples include transparent plastic containers, glass plates and containers, vases, syringes, color cathode ray tubes, fluorescent lights, beer bottles, ceramics, and porcelain. Of course, the scope of application of the ink of the present invention is not limited to the above.

[Implementation of the invention]

Next, examples of the present invention will be shown.

Example 1 Titanium oxide powder, rutile type (A-220, ACC 0-
Equivalent to 310 (manufactured by Ishihara Sangyo), xylene resin (manufactured by Mitsubishi Gas Chemical) dissolved in 15 parts and 70 parts of cyclohexanone 1
5 parts were dispersed in a paint shaker (manufactured by Toyo Seiki) for 1 hour, 1.5 parts of sodium thiocyanate and 100 parts of methyl ethyl ketone were added, and the mixture was stirred for 30 minutes in a hole bar. 3μ
Filter with suction using an m filter to remove coarse particles. Further, 501 parts of methyl ethyl ketone containing 0.5 parts by weight of zinc octate are added and mixed by shaking. In this way, tp can be used as an ink for inkjet recording! An ink having f properties was obtained.

That is, the above ink has the temperature-viscosity characteristics shown in FIG. 1, the temperature-surface tension characteristics shown in FIG. 2, the temperature-resistivity characteristics shown in FIG.
4 μm, with a particle size distribution shown in Table 2 A. Printing is performed by ejecting ink using an inkjet injection device with a nozzle orifice diameter of 75 μm, using a normal device except for applying a pressure of 4.5 Kf/cit. 11
By applying a vibration of 8 kHz, characters of 28 vertical dots x 28 horizontal dots can be printed. The objects to be printed were glass, black plastic, and steel plate coated with a high-temperature oxide film.

In either case, the printing is good, the printing is completed after being left for 80 to 120 seconds, and it does not come off even if you rub it with your fingers, and it does not stick to your fingers. In the case of crow (fishing soda glass for window glass, single-sided frosted glass), the diameter of the inkjet printed on the smooth surface after drying was 95 μm. On the frosted glass surface, the dot diameter was $-1: 160 μn]. In all cases, the white color had sufficient hiding power and the printed characters were clearly legible.

As other samples, when printing was performed on a polycarbonate molded plate containing 7% carphone powder, which is a black plastic, and a molded plate made of acrylonitosol-butadiene-tyrene (ABS) resin containing 12% carphone powder, the diameter of the print was They were respectively 220° and 240 μm'″C. In this case as well, there was no bleeding and a good white print was obtained.

The copper plate and the cold rolled steel plate (JIS G-3141
), carbon steel plate (AISI 1080), ordinary finish steel plate (JIS G3304), general steel pipe (JIS G3
421) and chemical industrial steel pipes (JIS G3426), clear white printing was also obtained.

Example 2 Titanium oxide (same as Example 1)...15 Heavy production department Rosin-modified xylene resin (manufactured by Mitsubishi Kasu Chemical Co., Ltd.)...
・・・・・・40 Cyclohexanone ・・・・・・・・・
・60 ethanol ・・・・・・
...20 The above material is passed twice in a sand mill to disperse it, 50 parts of ethanol and 20 parts of sodium thiocyanate are added, and the mixture is stirred in a whole mill for 30 minutes.

Filter by suction through a 3 μm filter to remove coarse particles. Plus octenoic acid. Methyl ethyl ketone 4C) containing lead 0.5 double button part: Add @ copper part and stir by stirring.

As a result, an ink having properties suitable for use in ink binding 1 for inkjet recording was obtained. That is, the above ink has a viscosity of 8.3 CP (20°C 1 surface tension 43 c
line/Cm, resistivity 500Ω・crIl, Lumi 1.
1. The average particle size was 0.4 μm, and the particle size distribution shown in Table 2 C was shown. Similarly to Example 1, similarly good printing was obtained with this ink.

Example 3 Titanium oxide powder (same as Example 1) 13 parts by weight Rosin-modified maleic acid (manufactured by Hitachi Chemical) 40
Nitrocellulose (Daicel HLx74)...2.0
Cyclohexanone ・・・・・・・・・
20 ethanol ・・・・・・
...42 Ethyl acetate ...
・・・・・・・・・5 Methanol
・・・・・・・・・・・・・・・5 The above material was passed through Santomil twice to disperse it, and 72 ammonium thiocyanate was obtained.
100 parts of ethanol and stir thoroughly. Filter by suction through a 3 μm filter to remove coarse particles. Further, the above part of FNO 1940 containing 1 part of Zinc Maketenate 05 weight was mixed by shaking at 11 times the strength.

As a result, an ink was obtained which deteriorated the characteristics that could be used as an ink for inkjet recording. That is, the above ink has a viscosity of 2.1CP (20tZ') and a surface tension of 2.
3 dyne/an, resistivity 1050Ω・CrIz
, a specific gravity of 104, an average particle diameter of 04 μm, and a diameter distribution shown in Table 2. Further, as in Example 1, good imprinting results were obtained on similar articles.

Implementation Reli 4 Titanium oxide (same as Example 1)...11! 'M
Bu-Ntel Gum (manufactured by Bu-Yorin Sangyo) ・・・・・・・・・
・4.3 Cyclohexanone ・・・・・・
・・・・43 Ecnor
・・・・・・・・・
40 Ammonium thiocyanate ・・・・・・
...1.5 Disperse the above in a ball mill for 15 hours,
After adding 100 kS of methyl ethyl ketone and stirring thoroughly,
3μn] Filter by suction through a filter to remove coarse particles.

As a result, an ink having an inertia of A that can be used as an ink for inkjet recording was obtained. That is, the above ink, viscosity 1.8CP (20°C), &Jo'jJi
Force 35 dyne/z+, resistivity 800Ω'ffi
, specific gravity 1.11, average particle size 0.4 μm, and the particle size distribution of M2iF. Further, as in Example 1, good results were obtained for printing T' using the Infusiera) N (2 recording device).

implementation? l15 Titanium oxide powder (same as Example 1) 20 parts by weight Ketone resin (manufactured by Hitachi Chemical)
・20 methyl ethyl couptons ・・・・・・
・・・50 ethanol ・・・
...10 Sodium thiocyanate
・・・・・・・・・2 Place the above items in a paint shaker (
(manufactured by Toyo Wa-sama) for 2 hours. Thereafter, 100 parts of methyl ethyl ketone was added, thoroughly stirred, and suction filtered through a 3 μm filter to remove coarse particles.

As a result, an ink having characteristics that can be used as an ink for inkjet recording was obtained. That is, the above ink has a viscosity of 9.8 CP (20 C) and a surface tension of 51 d.
Yne/cln, resistivity 430Ω・crn, specific gravity i1.21, average particle size 04 p m* 'j4' = 2
&h'') particle size distribution. Also, as in Example 1, good results were obtained with good printing on similar articles.

Example 6 Titanium oxide powder (same as Example 1) 40 Heavy Inspector Rosin modified maleic acid (same as Example 3) 15 Methanol 1
0 ethanol ・・・・・・・・・
・12 Isoproper Tools ・・・・・・・
・・・20 Ethyl acetate ・・・・・・
・・・・・・・・・5 Disperse the above ingredients in a paint shaker (manufactured by Toyo Seiki) for 2 hours. He is ethanol 100
1 part and 2 parts of lithium nitrate were added, optically stirred, and suction filtered through a 3 μm filter to remove coarse particles.

As a result, an ink that can be used as an ink for inkjet recording was obtained. That is, the above ink t has a viscosity of 13.5 CP (20C) and a surface tension of 27.
5dYne/cm, resistivity 910Ω'an, specific gravity 1.
5. Average particle size is 04 μm, which exceeds the particle size distribution in Table 2 B.

As in Example 1, good prints were obtained on similar articles.

Example 7 Titanium oxide (anatase type, manufactured by Wako Juncho)...
...200 Chongdu Chongtian gin-modified maleic acid (same as Example 3)...
...4.0 parts by weight Nitrocellulose (actual m 9
Same as +13, )・・・・・・・・・Triple 1 part cyclohexanone ・・・・・・・・・25. O
il[part ethanol ・・・・・・・・・
35.0 weight (ti part ethyl acetate...
・・・・・・・・・1. Double valve part methanol
・・・・・・・・・・・・30 heavy needle nitrified lithium
......20 parts by weight The above mixture was sufficiently stirred and suction filtered through a 3 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 8.5
CP (20C), surface tension 35dyne/crn,
It showed a resistivity of 700Ω·m and a specific gravity of 115.

Example 8 Zinc white (ZnO, manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.) 18 parts by weight Ketone resin (same as Example 5) 10 parts by weight Nitrocellulose (same as MFF1J3) ...
・・・・・・・・・5.0 weight 1 part cyclohexanone
・・・・・・・・・30.0 Duon 1 part Improvyl alcohol ・・kawa・・35.031jii [Ethyl acetate ・・・・・・・・・・・・1.5
lj book part methanol・・・・・・・・・
・250 heavy storage part chi-blade cyanic acid sorter ・・Mark・・
Stir the 2.0 plate t1 (part above 1-") by optical separation, filter it with suction through a 3 μm filter, and remove the coarse particles. As a result, , sticky fi 7.8
CP (21-1 CI 't W< surface force 3゜dyne
/cYn, , 1<resistivity 5soΩ'ffi, specific gravity 1.
10 was shown.

Implemented 119 Lidobore (Z'S 10B aS 04 + homemade) 28 parts by weight Rosin modified t1 xylene resin (same as Example 2)...
・・・・・・LoMH part Nito part Upper trocellulose Reli 3) ′・・・・・・
・・・・・・・・・551 Lid part cyclohexanone・Old・・・・・・40. O3-
[Part ethanol ・・・・・・・・・25
．． 1 part ffr ethyl acetate... mark... old... 1,8 parts 4 parts methyl ethyl ketone...
...3 (1.0 wt% ri part lithium nitrate
・・・・・・・・・Group・2.5 @ Press the upper part of the bow sufficiently with your finger, suction filtration with 37xm filter 1-1,
Remove coarse particles. As a result, the ink has a viscosity of 6.
8 CP (20c), ii tension 29dyne/D
1゜Example 10m white (2PhCO3・Pb(OH) 2! fp light pure pongee medicine) 1゜Example 10 showing a ratio of 1050 Ω'cm and a specific gravity of 1.18. 20 parts by weight xylene resin (same as Example 1) 31 negative parts Nitrocellulose (same as Example 3) 35 parts by weight Cyclo-\xanone Old ...3ooMM
4 Partly isoglobil alcohol light...38. o Part by weight Ethyl acetate...Scream...1.51
Bud methanol Town/River...5. On
Thiocyanic acid sorter 28 Multi-image section Thoroughly stir the above material and filter with suction through a 3 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 7.8 CP (20C) and a narrow surface tension of 29 dYn.
e/cnr, resistivity 480Ω・clll, ratio N1.1
8 was shown.

9 (Example 11 Sulfurized Oki lead tzns manufactured by Wako Junkuwa)...23i 1 part ketone resin (same as Example 5)...20''i Lid part nitrocellulose (same as Example 3) ) ・・・・・・・・・・・・3.0 oil lid part cyclohegisanone ・・・old・・・55.03ji parts ethanol ・・・・・・・・・aooii+s ethyl acetate ・・・・・・...35 heavy details ethylene glycol monoethyl ether...
...15.0 heavy 1 part lithium nitrate ...4
The above mixture was thoroughly stirred for 5 hxs and filtered with suction through a 3 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 9.8 CP (20C) and a surface tension of 32 d.
yne/cm, resistivity 650Ω'Q7+, specific gravity 1.
18 was shown.

Example 12 Basic lead sulfate (2Pb804/pbo, manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.)
......15.0 heavy bud rosin modified maleic acid (same as Example 3)...
...501 parts Nitrocellrone (same as Example 3)...3. ol,
Okibe cyclohexanone ・・・・・・・・・35
．． O3'-111i ethanol・Old・・
...28. (l 73 parts ethyl acetate
・・・・・・・・・・・・1.51 Keibu Methanol
・・・・・・・・・・・・5.0! itl sodium thiocyanate ・・・・・・・・・・・・2.
1 part by weight of the above is sufficiently stirred and suction filtered through a 3 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 8.6 CP (20c), a 9-plane tension of 3° dYne/cm, a resistivity of 550 Ω'cm, and a specific gravity of 1.1.
8 was shown.

Example 13 Zirconium oxide (ZrO, manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.)...
...120 parts by weight rosin-modified maleic acid (same as Example 3)...
...50 parts Nitrocellrone (same as Example 3) ...21 parts by weight cyclohexanone ...3505
0tl tanol ・・・・・・・・・25
．． 0 parts by weight ethyl acetate...
...30-layer lid in-propyl alcohol...
...300i-Ji part lithium nitrate
30 parts by weight The above mixture was thoroughly stirred and suction filtered using a 3 μn filter to remove coarse particles. As a result, the above ink has a viscosity of 5.8 CP
(20r), surface tension of 28 dyne/crn, resistivity of 480 Ω'm, and specific gravity of 109.

Example 14 Antimony white (Stag's, manufactured by Wako Tsumugi Pharmaceutical)...
...15.0 type needle part ketone resin (same as Example 5) ...100 parts by weight nitrocellulose (same as 'jlllJ3) ...
...50 parts by weight cyclohexanone ...40.0
Heavy tS ethylene glycol monomethyl ether...
...25.0 parts by weight Ethyl acetate ...2
5-layer shelf methanol...1 old...3
13i [partial sodium thioneanate, old...
...2.5 parts by weight The above mixture was thoroughly stirred and suction filtered through a 3 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 6.5 CP (20 tl:'), a surface tension of 29 dyne 7 cm, and an M resistivity of 650 Ω・C.
1n and specific gravity of 1.10.

Example 15 Tin oxide (8n02 * manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.)...25 parts by weight Ester gum (same as Example 4)...13 parts by weight Nitrocellulose (same as lifFIJ3)...
・・・・・・・・・2. O11 heavy cyclohexanone
...Old...40.0 weight 1 part ethanol
・1 river...25. Oi Okibe ethyl acetate
River... Old... 3.0 weight 1 part isopropyl alcohol... River... 10. OMt part lithium nitrate
・・・・・・・・・・・・2.8 parts by weight The above material was thoroughly stirred, filtered with suction through a 3 μm filter,
Remove coarse particles. As a result, the ink has a viscosity of 8.
5 CP (20C), surface tension 32 also dy mouth e/
It showed crIj, Ii resistivity of 750 Ω·m, and ratio i of 1.20.

When the inks of Examples 7 to 15 were printed using an inkjet recording device in the same manner as in Example 1, good results were expected.

Comparative Example 1 Titanium oxide (same as Example 1)...210 parts by weight Rosin-modified maleic acid (same as Example 3 and (1))...
・・・・・・・・・35 Heavy Nitrocellulose (same as Practical 3) ・・・・・・・・・35 Heavy Nitrocellulose ＼Xanone ・・・・・・・・・20. O1fHJ ethanol...old...35. O3 triethyl acetate ・・・・・・・・・・・・1
．． Five layers of anbu inpropyl alcohol・・・・・・・・・
・25. Oki, part i sodium thionate...
...Old... 2.5 parts Stir the above ingredients thoroughly,
Filter with suction through a 4 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 8.0 CP (2Or)
, surface tension 29dYne/crn, m resistivity 850Ω
・m, specific gravity 1.08, average particle size and particle size distribution of the second Shishi G.

Comparative Example 2 Titanium oxide ('A Same L as Example 1)...20.0] ii
xylene resin (same as Example 1) 48 parts by weight Nitrocellulose (same as Example 3) 30 parts cyclohexanone・230 parts by weight Inglobil alcohol ・・・・・・・・・41
．． OMiA part ethyl acetate...
...i, sz 1 part methanol...
Group... River... 31i Iibe thioneanate...
・・・・・・・・・32-layer lid part Stir the above material thoroughly and suction filtrate it with a 4 μm filter to remove coarse particles. As a result, the above ink has a viscosity of 8.8 CP (20
C), surface tension 27d)'ne/cn+, resistivity 78
0Ω'ffi specific gravity was 1.12, and the average particle size and particle size distribution of the second iH were shown.

Comparative Example 3 Titanium oxide (same as Example 1)...280 yi 2 parts [I gin-modified maleic acid (same as Example 3)...
・・・・・・・・・4.5 ii Firewood part nitrocellrone (same as Example 3) ・・・・・・・・・・・・4.5] ji4 part cycloheginon ・・・・・・...28. OM t
rJ,' methanol・kawa・dan・45
．． 0, i, it part ethyl acetate...
......2.5iii parts Isoflobil alcohol Old...30.0%@part Lithium nitrate... Old...30 heavy parts Stir and filter through a 5μIn filter to remove phase particles. As a result, the above ink has a viscosity of 7.9
CP (20r), N? ffi tension 33dYne
/cm, M resistivity 980Ω'm, ratio xx, 12, 2nd
The average particle size and particle size distribution of the batter ■ are shown.

When the inks of Comparative Reli 1 to 3 were printed using an inkjet recording apparatus in the same manner as in Example 1, the printing stability was not good, and some missing spots occurred in the printing17. The nozzle was easily clogged.

Furthermore, the dispersion stability was not good (see FIG. 4), and the ink of Comparative Example 2.3 did not have good internal dispersibility.

The measurement was carried out as follows, as shown in the white area change FiAR'5 diagram in FIG. ; Pour ink to a depth of 130 mm into a crow container with an 18φ diameter and a height of 150 fins, and let it stand naturally. The rate of change in the white part (A in the figure) at this time was plotted. Similarly, in FIG. 5, A indicates a white portion, B indicates a transparent portion, and C indicates ink, and the white portion was determined as %J=AX100/C.

Table 3 shows the influence of the particle size distribution of titanium oxide in the inks of Examples 1 to 6 and Comparative Examples 1 to 3 on the ink characteristics.

Table 3 Ink properties due to changes in particle size distribution of titanium oxide [Effects of the invention] As explained above, according to the present invention, viscosity, electrical resistivity,
A white ink composition for inkjet recording with excellent stable dispersibility of pigment particles can be obtained, and furthermore, this ink composition can be used to clearly print on black and dark-colored articles.

Brief description of the drawing

Claims (1)

[Claims] 1. Contains a coloring agent, an organic solvent, a binder resin, and a resistivity regulator, and has a temperature of 200°C under usage conditions (51 to 40C).
A white ink composition for inkjet recording having a resistivity of 0Ω·Crn or less and a viscosity of 1 to 15CP, characterized in that the colorant is titanium oxide. 2. The ink composition according to claim 1, wherein the titanium oxide has a particle size of 3 μm or less, and the titanium oxide content in the ink composition is 5 to 40% by weight.